Montmorenci, Indiana Weather Forecast Discussion

283
FXUS63 KIND 121716
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
116 PM EDT Fri Sep 12 2025
.KEY MESSAGES...
- Progressively hotter weather for the weekend and into early next
  week with multiple days with highs above 90
- A small threat for showers and thunderstorms exists Saturday night
  and early Sunday, otherwise continued dry weather supports further
  expansion of drought conditions into next week
- Dry fuels and low RH values each afternoon may lead to an elevated
  fire threat, but light winds should limit overall concerns
&&
.FORECAST UPDATE...
Issued at 947 AM EDT Fri Sep 12 2025
Forecast is in good shape this morning. Only some patchy thin cirrus
was across the area, and the sunshine with a dry atmosphere is
allowing temperatures to rise nicely.
Some cirrus will move in at times today along with a few cumulus,
but skies will average sunny to mostly sunny. Highs in the 80s still
look good, so didn`t make any changes there. Adjusted hourly
temperatures to match current trends in observations.
&&
.SHORT TERM (Today and Tonight)...
Issued at 304 AM EDT Fri Sep 12 2025
Clear skies and light winds were prevalent across the Ohio Valley
early this morning. With ideal radiational cooling conditions...
temperatures at 06Z ranged from the lower 50s in our typical cool
locations to the mid 60s in the Indy metro.
A broad surface ridge covering much of the eastern half of the
country combined with an expanding ridge aloft centered over the
southern Plains will produce a continuation of the dry and
increasingly warmer pattern through tonight and into the weekend
and beyond.
Dewpoints early this morning are highest across southern portions of
the forecast area and hint at just enough moisture in the near
surface layer to potentially produce localized fog through daybreak.
Any fog that does develop will diminish rapidly once the sun rises.
The rest of the day will be mostly sunny with a few cirrus drifting
down the eastern flank of the upper ridge and perhaps a few higher
based cu in the afternoon. Light E/SE winds are expected before
winds diminish again tonight to near calm.
RH values will drop to minimum levels around 25-30% this afternoon
which support steadily increasing fire danger concerns despite
lighter winds. Will touch on this in greater detail in the Fire
Weather section below.
Temps...low level thermals are supportive of highs in the mid and
upper 80s this afternoon with warmest temperatures in the Wabash
Valley in closest proximity to the upper level ridge. Incorporated
MOS guidance into lows for tonight as suspect the blended model data
is not capturing the variance in overnight lows due to excellent
radiational cooling well. This led to lows being nudged down a few
degrees...particularly over the eastern half of the forecast area.
&&
.LONG TERM (Saturday through Thursday)...
Issued at 304 AM EDT Fri Sep 12 2025
The primary focus through the long term period will be on the
increasing heat and potential for exacerbating drought conditions.
The upper level ridge will continue building into the Central US
this weekend with light and calm winds near the surface. Despite
being just a few days away, forecast confidence remains low for
portions of this weekend`s weather. The general synoptic pattern is
consistent across ensemble output, but the variance is associated
with the potential for for ridge-riding shortwaves. The main
difference is on where the bulk of the 850-700mb WAA will occur
through Saturday, of which will have a direct correlation on where
any shortwave ridge develops and if the subgeostrophic flow
beneath the passing wave over eastern Canada will pass through the
Great Lakes region. While there will be some moisture return into
the Ohio Valley by Saturday, instability values will be fairly
meager. That said, in the case of a strengthening jet across the
Upper Midwest, increase shear could create a favorable environment
for thunderstorm organization. At this point, confidence is
fairly high in at least some thunderstorms across the Great Lakes
region, but confidence is on the lower end if much of it reaches
as far south as central Indiana. Beneath the ridge, much different
conditions are expected, with weak tropospheric winds and
building PBL temperatures. Highs will likely be in the mid 80s to
near 90.
The lack of confidence in Saturday to Early Sunday`s forecast
provides cascading impacts for the rest of the long term, and
therefore forecast confidence continues to decrease Sunday into
Monday. General consensus in the overall airmass will remain warmer
than normal, with the potential caveat of lingering upper level
cloud cover. Currently leaning towards a more persistent pattern
with the upper level ridge helping to push the aforementioned low
pressure further east into the Northeastern states, but will have to
continue to monitor forecast trends. Temperatures Sunday through at
least midweek should see highs in the low 90s for most of the area
with lows in the 60s. Meanwhile, afternoon RH values should
generally be in the 30-40% range but could see lower amounts with
days that get ample mixing.
Outside of locations that see any spotty precipitation this weekend,
it`ll be another dry 7 days for much of central Indiana which puts
many locations as seeing little to no rain for the last 3 weeks.
This combined with the stretch of much above normal weather is
expected to lead to the expansion of drought conditions across the
state and could cause additional fire weather concerns.
Models are hinting at the chance of more widespread rain just beyond
the long term period so will continue to monitor the potential for
much needed rain as it gets closer.
&&
.AVIATION (18Z TAF Issuance)...
Issued at 115 PM EDT Fri Sep 12 2025
Impacts: None
Discussion:
VFR conditions are expected through the period. Mainly cirrus is
expected through tonight, then some mid cloud will move in Saturday
morning. Winds will be light overnight and less than 10kt Saturday.
There is the potential for a weakening thunderstorm complex moving
in from the northwest after 15Z, but right now confidence is not
high enough to include. Potential for convection would continue past
18Z for KIND.
&&
.FIRE WEATHER...
Issued at 304 AM EDT Fri Sep 12 2025
The lack of any significant rainfall since late August has resulted
in abnormally dry and minor drought conditions to develop across
Indiana. With little rain in the forecast for the next 7 days,
confidence continues to increase in slightly elevated fire
weather conditions each afternoon as daily min RH values fall
into the 25 to 35% range.
The major factor keeping the fire weather threat lower is the
lack of wind. Despite deep mixing, very weak low level flow should
keep winds under 10 mph through the period. If no appreciable
rainfall is observed this weekend, the fire weather threat will
likely persist into mid month. Will continue to monitor the
extended forecast for increasing fire weather concerns.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...50
SHORT TERM...Ryan
LONG TERM...KF
AVIATION...50
FIRE WEATHER...Ryan

NWS IND Office Area Forecast Discussion